Microwave-Assisted Nafion-H Catalyzed Friedel–Crafts Type Reaction of Aromatic Aldehydes with Arenes: Synthesis of Triarylmethanes

Generation of C(sp3)-CAr bonds in the synthesis of triarylmethanes (TRAMs): comprehensive progress since 2009

Triarylmethanes are useful compounds in materials science and medicinal chemistry. These moieties are important constituents of dyes and pharmaceuticals. These scaffolds are synthesized either by Friedel-Crafts alkylation of aldehydes and arenes or by the functionalization of diarylmethanes. The development of effective catalytic systems and the discovery of highly regio- and stereoselective methods using Brønsted or Lewis acid catalysts represent particularly important achievements in this field. This review explores the detailed documentation of the various catalytic strategies witnessed since 2009 for the synthesis of triarylmethanes, which could arouse the interest of readers in organic synthesis.

Gram-Scale Synthesis of Substituted Triarylmethanes

In this paper, a high-yield, open-vessel route for the facile-operational, gram-scale synthesis of functionalized triarylmethanes (TRAMs) is described via silica coated magnetic nanoparticles of modified polyphosphoric acid (NiFe2O4@SiO2-PPA)-mediated intermolecular Friedel-Crafts reaction of substituted arylaldehydes with 2 equivalents of oxygenated arenes under environmentally friendly reaction conditions. Among the overall reaction process, only water was generated as the byproduct. Various reaction conditions are investigated for efficient transformation.

Synthesis and Biological Evaluation of Taurine-Derived Diarylmethane and Dibenzoxanthene Derivatives as Possible Cytotoxic and Antimicrobial Agents

The series of novel taurine-derived diarylmethanes and dibenzoxanthenes was synthesized starting from simple commercially available precursors via modular three-stage approach. All the newly synthesized compounds were screened for in vitro antibacterial and antifungal activity, as well as cytotoxicity towards normal and cancer cell lines. Some of the synthesized compounds exhibited 2-4-fold higher activity against S. aureus, E. faecalis and B. cereus compared with Chloramphenicol. In contrast to Chloramphenicol, the tested compounds also showed bactericidal, rather than bacteriostatic effect, which makes them promising candidates for further studies.

Metal- and solvent-free synthesis of aniline- and phenol-based triarylmethanes via Brönsted acidic ionic liquid catalyzed Friedel-Crafts reaction

A beneficial, scalable and efficient methodology for the synthesis of aniline-based triarylmethanes has been established through the double Friedel-Crafts reaction of commercial aldehydes and primary, secondary or tertiary anilines using Brönsted acidic ionic liquid as a powerful catalyst, namely [bsmim][NTf2]. This protocol was successfully performed under metal- and solvent-free conditions with a broad range of substrates, giving the corresponding aniline-based triarylmethane products in good to excellent yields (up to 99%). In addition, alternative aromatic nucleophiles such as phenols and electron-rich arenes were also studied using this useful approach to achieve a diversity of triarylmethane derivatives in high to excellent yields.

One-Pot Synthesis of Novel Dibenzoxanthenes, Diarylbutanes, and Calix[4]resorcinarenes via Consecutive Pyrrolidine Ring-Closure/Ring-Opening Reactions

Herein, we report the approach to the otherwise hardly accessible dibenzoxanthenes, diarylbutanes, and calix[4]resorcinarenes possessing urea moieties based on the reaction of N-(4,4-diethoxybutyl)ureas with electron-rich aromatics in strongly acidic media. Unlike the previously developed methods, the proposed approach benefits from one-pot procedure and allows to obtain the target compounds with much higher yields.

Organic Synthesis Using Environmentally Benign Acid Catalysis

Recent advances in the application of environmentally benign acid catalysts in organic synthesis are reviewed. The work includes three main parts; (i) description of environmentally benign acid catalysts, (ii) synthesis with heterogeneous and (iii) homogeneous catalysts. The first part provides a brief overview of acid catalysts, both solid acids (metal oxides, zeolites, clays, ion-exchange resins, metal-organic framework based catalysts) and those that are soluble in green solvents (water, alcohols) and at the same time could be regenerated after reactions (metal triflates, heteropoly acids, acidic organocatalysts etc.). The synthesis sections review a broad array of the most common and practical reactions such as Friedel-Crafts and related reactions (acylation, alkylations, hydroxyalkylations, halogenations, nitrations etc.), multicomponent reactions, rearrangements and ring transformations (cyclizations, ring opening). Both the heterogeneous and homogeneous catalytic synthesis parts include an overview of asymmetric acid catalysis with chiral Lewis and Brønsted acids. Although a broad array of catalytic processes are discussed, emphasis is placed on applications with commercially available catalysts as well as those of sustainable nature; thus individual examples are critically reviewed regarding their contribution to sustainable synthesis.

Synthetic methodologies of achiral diarylmethanols, diaryl and triarylmethanes (TRAMs) and medicinal properties of diaryl and triarylmethanes-an overview

This review covers the synthesis of achiral diarylmethanols, diaryl and triarylmethanes and the bioactivities of diaryl and triarylmethanes during 1995 to 2013.